Barriers to health care utilization limit drug users' interaction with the primary health care system, resulting in episodic health care received through Emergency Departments (ED) and Urgent Care Centers (UCC). Since 1994, the BMC ED and UCC have provided substance abuse screening as standard of care. This program employs the Brief Negotiated Interview (BNI) to assess readiness to change and offer intervention alternatives and referrals to substance abusing patients. Drug users' high rates of STDs, HIV, and Hepatitis C (HCV) and utilization of EDs and UCCs as usual sources of health care support the introduction of sexual behavior intervention in the ED and UCC setting. The proposed study will apply existing BNI theory and research to a new behavioral context. The proposed project is a collaborative effort to adapt the BNI to encourage safe sex behaviors to prevent gonorrhea, chlamydia, and HIV among male and female ED and UCC patients age 18-44 years who use heroin and/or crack/cocaine and are not in treatment. We will enroll and 1:1 randomize 3,340 patients to intervention (safe sex BNI) or control (standard counseling) over a 2.5-year period, with 6- month and 12-month follow-up. Enrollment will begin Month 9 of Year 1 and Follow-Up will be completed Month 3 of Year 5. The goal of the proposed project is to determine the effectiveness of safe sex BNI counseling to prevent STDs and HIV by comparing cumulative STD incidence and frequency of safe sex behavior between intervention and standard counseling (control) groups over a one year follow-up period. STD and HIV will be diagnosed by specific laboratory assay at baseline, 6-month, and 12-month follow-up. Sexual and drug using behavior will be by participant self-report at baseline, 6-month, and 12-month follow-up, with biochemical testing of hair samples for opiates and cocaine at enrollment and 12-month follow-up. Sexual behavior risk will be measured in terms of proportion of vaginal and anal sex acts protected by condom use and condom use at last sexual act, by sexual partner type. Stage of change will be assessed by the Readiness Ruler. Differences in cumulative incidence between intervention and control groups will be evaluated using Poisson regression with random effects modeling if needed. Differences in safe sex behavior between intervention and control groups will be evaluated using logistic regression. After assessing intervention effect in the base model, we will assess intervention effect controlling for age, gender, race, and baseline readiness to change and sexual and drug using behavior. We will conduct exploratory analyses for the potential interaction and mediating effects between intervention status and abstinence from drug use on incidence of STDs and self-reported behaviors. An effective, brief intervention for safe sex behaviors to reduce STDs and HIV among drug users in ED and UCC settings may provide a sustainable intervention opportunity for drug users who are otherwise difficult to access.